Alkylated diamines have been known for a substantial period of time and find use in the preparation of polyurethane elastomers. The diamines are typically used in that form as chain extenders for polyurethanes, i.e., forming a short chain urea linkage to strengthen the elastomer. As is known, the alkyl group alters the reactivity of the amine thus giving the composition unique processing properties for producing polyurethane elastomers.
Two types of synthesis techniques have been used to produce alkylated aromatic amines, such as, an alkylated toluenediamine. One of the earliest techniques used to prepare an alkylated aromatic diamine employed a Friedel-Crafts alkylation of an aromatic hydrocarbon, then dinitration of the alkylated aromatic hydrocarbon followed by reduction of the nitro groups to amine groups. The diamine could be converted to the diisocyanate by reaction with phosgene. Another technique for producing an alkylated aromatic amine involved nitration of an aromatic hydrocarbon, followed by reduction to the amine and then alkylation of the amine.
Aromatic compositions and particularly aromatic amines having unsaturated organo substituents are known. They have been prepared by alkenylation of aromatic compositions with diolefins. Some patents which show the manufacture of aromatic compositions having unsaturated organo substituents include:
U.S. Pat. No. 2,403,963 which discloses the reaction of benzene and butadiene in the presence of a boron trifluoride catalyst. Phenylbutenes are produced.
U.S. Pat. No. 2,471,922 discloses that aromatic hydrocarbons, which include phenols and aromatic halides, can be reacted with 1,3-diolefins to produce alkenyl derivatives. Examples of low-boiling 1,3-diolefins which can be used in the alkenylation include 1,3-butadiene, 1,3-pentadiene and so forth. Catalyst systems included boron trifluoride and boron trifluoride-phosphoric acid systems.
U.S. Pat. No. 3,865,889 discloses the preparation of an alkenylated aromatic hydrocarbon such as those obtained by reacting butadiene with an alkylbenzene, e.g., toluene or xylene. An alkali metal promoter is used to catalyze the reaction.
U.S. Pat. No. 2,843,565 discloses the production of butenyl-phenol-aldehyde resins which involves the reaction of an alkenylphenol, with formaldehyde. Conjugated dienes such as piperylene, cyclopentadiene, 1-chloro-2-methyl-butadiene are reacted with phenols in the presence of phosporic acid catalyst and the reaction product then reacted with formaldehyde.
West German 1,079,628 discloses the preparation of cyclopentenyl-substituted aromatic amines by reacting cyclopentadiene at secondary or tertiary aromatic amine substrates. Aniline, N-methylaniline, chloroaniline, and phenylenediamine are suggested aromatic amine candidates.